Bioconversion of Glycerol to Dihydroxyacetone by Immobilized Gluconacetobacter Xylinus Cells

Cathryn Sesengel Black and Giridhar Raghavan Nair

Abstract—In this study, Gluconacetobacter xylinus cells were immobilized in calcium alginate and chitosan-coated alginate beads. The immobilized cells were used in the conversion of glycerol to dihydroxyacetone (DHA) in a stirred-tank reactor. Fermentations using free cells and 2% (w/v) initial glycerol yielded 6.3 gL-1 DHA after 60 h. This corresponded to a productivity of 0.11 gL-1h-1. Using 2% (w/v) initial glycerol and 0.3 vvm air flow, G.xylinus cells immobilized in alginate beads gave a DHA concentration of 12.7 gL-1 and a productivity of 0.09 gL-1h-1. The final DHA concentration and productivity of G.xylinus cells immobilized in chitosan-coated alginate beads were 11.9 gL-1 and 0.07 gL-1h-1, respectively, at 0.3 vvm air flow. Final DHA concentration and productivity further increased to 17.0 gL-1 and 0.11 gL-1h-1 at 1.0 vvm airflow. Chitosan coating provided greater stability to the alginate beads with increased aeration rate.

C. S. Black is with the University of Waikato, New Zealand (e-mail: Cathsblack22@gmail.com).
G. R. Nair is with the Engineering Department at the University of Waikato, Hamilton, NZ. (e-mail: Giridhar@waikato.ac.nz).